The field of invention is the composition and application of catalysts useful for the production of insulating polyurethane foam produced with blowing agents containing a halogen.
Polyurethane foam compositions are typically prepared by reacting an isocyanate and a premix which consists of isocyanate-reactive components such as a polyol. The premix optionally also contains other components such as water, flame retardants, blowing agents, foam-stabilizing surfactants, and catalysts to promote the reactions of isocyanate with polyol to make urethane, with water to make CO2 and urea, and with excess isocyanate to make isocyanurate (trimer). The blowing agent in the premix is usually a liquid or gas with a boiling point sufficiently low to be vaporized by the heat released during the polymerization reaction. Examples of blowing agents useful in the production of insulating polyurethane foam include but are not limited to hydrofluorocarbons, hydrofluoroolefins, hydrofluorochloroolefins, hydrochlorofluorocarbons, formates, and hydrocarbons. The proper selection and combination of the components in the premix and the isocyanate can be useful for the production of polyurethane foam that is spray applied, poured in place, and used in applications such as refrigerators, freezers, hot water heaters, insulation panels, garage doors, entry doors, and other various applications where insulation is desired. For some of these applications, the premix is stored for one day up to one year before being reacted with isocyanate to generate polyurethane foam. This is common in sprayfoam applications, where drums of premix and isocyanate are shipped to field locations for on-site application. Thus, it is desirable for the premix of an insulating foam formulation to be both chemically and physically stable. However, the catalysts that are useful to promote the polyurethane reaction can also participate or induce undesired reactions with the blowing agents present in the premix resulting in reduced storage stability. These undesired reactions are prevalent in blowing agents that contain halogens, and are especially problematic in halogenated blowing agents containing unsaturation and olefinic carbons. Common amine catalysts useful for the production of polyurethane foam include tertiary amines, such as N,N,N′,N″,N″-pentamethyldiethylenetriamine (available from Air Products as Polycat®-5) or 1,4-diazabicyclo[2.2.2]octane (available in solution from Air Products as Dabco®33LX) which are known to accelerate the urethane reaction promoting the formation of polyurethane polymers. However, tertiary amines are also know to react with halogen containing organic compounds causing deactivation of the tertiary amine catalysts resulting in a net decrease in the kinetic of the polymerization process. Reaction between tertiary amine and halogen containing organic compounds occurs more rapidly when the halogen atom is bound to an olefinic carbon because halogen-substituted olefins are susceptible to nucleophilic attack by tertiary amines. This results in a fast deactivation of the tertiary amine catalysts rendering the premix not active enough for reaction with the isocyanate. Deactivation of tertiary amine by reaction with halogen containing compounds can also occur in halogen containing aliphatic compounds via formation of a quaternary ammonium salt or dehydrohalogenation both pathways resulting in tertiary amine deactivation.
U.S. Pat. No. 3,280,214, which is hereby incorporated by reference in its entirety, describes an organopolysiloxane copolymer and a method for making the organopolysiloxane copolymer. The method includes a single step of producing a wide range of specific block copolymers of organopolysiloxanes. Specifically, the method uses tetramethylguanidine octoate to cure a block copolymer and produce a material with good adhesion to aluminum. The tetramethylguanidine octoate is an aliphatic salt and suffers from a drawback that is temperature dependent when used in curing of elastomeric polyurethane polymers.
U.S. Pat. No. 3,663,258, which is hereby incorporated by reference in its entirety, describes a coating composition containing a dye and tetramethylguanidine trichloroacetate in a solution of inert binder at a pH not higher than 3. The acidic solution of tetramethylguanidinium trichloroacetate is dissolved in the minimum amount of water and the solution is added to a solution of the dye and binder in a water miscible organic solvent. The acid is a very strong organic mono-acid and suffers from a drawback that it slows down the reaction considerably.
U.S. Pat. No. 3,391,113, which is hereby incorporated by reference in its entirety, describes thermo settable resin mixtures that include epoxy resin having a plurality of 1,2-epoxy groups. Tetraalkylguanidines are used to accelerate cure of dicyanamide-epoxy resin mixtures in powder form, prepared by grinding together dicyanamide and tetraalkylguanidine. The process suffers from a drawback that it requires grinding of solids and the composition requires dicyanamide to accelerate the cure of the epoxy resin.
U.S. Pat. No. 4,025,466, which is hereby incorporated by reference in its entirety, describes a process for preparing polyurethane foam. The process includes reacting a polyisocyanate and a polyol in the presence of a catalyst containing the chemical structure ═N—C═N— and a metal salt carboxylate. Tetramethylguanidine is used as a catalyst to make polyurethane foam together with carboxylate salts such as sodium formate and potassium acetate. The process suffer from a drawback that formate salts and/or acetate salts would significantly slow down the foaming process particularly in spray foam applications causing sagging of the mixture during application.
A process, a polyurethane composition, a polyurethane product, a process of producing a catalyst composition, and a catalyst that do not suffer from one or more of the above drawbacks would be desirable in the art.